White supremacist serial killer Joseph Paul Franklin was put to death Wednesday morning less than an hour after the U.S. Supreme Court refused to stay the execution.

Franklin was executed for a 1977 sniper killing at a suburban St. Louis synagogue, report CNN, the Associated Press and the St. Louis Post-Dispatch. He had also been convicted in seven other murders and claimed responsibility for 20 killings in all. Franklin’s motive was “religious and racial hate,” Missouri Gov. Jay Nixon said in a statement.

Franklin was executed by a single injection of pentobarbital, which is used to euthanize pets. He was declared dead at 6:17 a.m. The Supreme Court’s order refusing the stay (PDF) was issued at about 5:20 a.m.

Two federal judges had issued stays because of the drug issue and a claim of mental incompetence, but the St. Louis-based 8th U.S. Circuit Court of Appeals overturned the stays. Media witnesses said Franklin did not appear to express pain after he was injected, according to the Post-Dispatch.

Franklin had admitted shooting Hustler magazine publisher Larry Flynt because of interracial sex photos in the magazine. Flynt had joined with the American Civil Liberties Union to seek documents about the lethal injection process.

Prior coverage:

ABAJournal.com: “Serial killer who may have slain 22 people compares himself to Jesus, hopes for execution stay”